The present invention relates to the field of non-contact laser scanner profilometer systems and calibration techniques for such systems.
The present invention describes highly accurate techniques for calibrating 3D measurement systems. The theory and use of these inventions are introduced by examining how these inventions aid the construction and use of a non-contact laser scanning system. A body of useful prior art for this work is described in U.S. Pat. No. 6,441,908, issued to Johnston et al.
These and other advantages of the present invention will become more fully apparent from the detailed description of the invention hereinbelow.
The present invention is directed to a method for providing calibrated geometric data from a three dimensional measurement system, the method comprising: providing a reference object having a predetermined geometric structure; providing reference object geometric structure data in a first coordinate frame, wherein the reference object geometric structure data corresponds to the predetermined geometric structure; providing a three dimensional measurement system comprising: a measurement element that measures geometric data in a second coordinate frame from the reference object and from a target object; and a motion system that provides relative motion between the reference object and the measurement element, wherein the relative motion occurs in a third coordinate frame, wherein the three dimensional measurement system provides motion data in the third coordinate frame corresponding to the relative motion; acquiring a geometric data set comprising the measured geometric data from the reference object by the measurement element as a result of the relative motion provided by the motion system, wherein the geometric data set further comprises the motion data; determining a first transformational relationship between the second coordinate frame and the third coordinate frame, wherein the first transformational relationship is determined using the measured geometric data and the motion data contained within the geometric data set, and using the reference object geometric structure data; and providing calibrated geometric data in a single coordinate frame from the target object by using the first transformational relationship.
The present invention is also directed to a method for providing calibrated geometric data from a three dimensional measurement system, the method comprising: providing a reference object having a predetermined geometric structure; providing reference object geometric structure data in a first coordinate frame, wherein the reference object geometric structure data corresponds to the predetermined geometric structure; providing a three dimensional measurement system comprising: a measurement element that measures geometric data in a second coordinate frame from the reference object and from a target object; a first support system that supports the measurement element, wherein the first support system resides within a third coordinate frame, wherein the first support system is capable of supporting the measurement element in at least a first element position and a second element position; and a second support system that supports the reference object, wherein the second support system resides within a fourth coordinate frame, wherein the second support system is capable of supporting the reference object in at least a first object position and a second object position; wherein a first relative motion occurs between the measurement element and the reference object, wherein the three dimensional measurement system provides first motion data corresponding to the first relative motion, wherein the first motion data includes either or both first position data in the third coordinate frame from the first support system and first position data in the fourth coordinate frame from the second support system; and wherein a second relative motion occurs between the measurement element and the reference object, wherein the three dimensional measurement system provides second motion data corresponding to the second relative motion, wherein the second motion data includes either or both second position data in the third coordinate frame from the first support system and second position data in the fourth coordinate frame from the second support system; acquiring a first geometric data set comprising first measured geometric data from the reference object by the measurement element as a result of the first relative motion, wherein the first geometric data set further comprises the first motion data; acquiring a second geometric data set comprising second measured geometric data from the reference object by the measurement element as a result of the second relative motion, wherein the second geometric data set further comprises the second motion data; determining both a first transformational relationship between the second coordinate frame and the third coordinate frame, and a second transformational relationship between the first coordinate frame and the third coordinate frame, wherein both the first transformational relationship and the second transformational relationship are determined using the first measured geometric data and the first motion data contained within the first geometric data set, and using the reference object geometric structure data; determining both a third transformational relationship between the second coordinate frame and the third coordinate frame, and a fourth transformational relationship between the first coordinate frame and the third coordinate frame, wherein both the third transformational relationship and the fourth transformational relationship are determined using the second measured geometric data and the second motion data contained within the second geometric data set, and using the reference object geometric structure data; determining a fifth transformational relationship between the third coordinate frame and the fourth coordinate frame, wherein the fifth transformational relationship is determined using the second transformational relationship and the fourth transformational relationship; and providing calibrated geometric data in a single coordinate frame from the target object by using the fifth transformational relationship and using either or both of the first transformational relationship and the third transformational relationship.